Aircraft navigation instrument



June 15, 1943. w R LEAR 2,321,606

AIRCRAFT NAVIGATION INSTRUMENT Filed May 15, 1940 2 Sheets$heet l AUTOMATIC RADIO I omzcnow FINDER /7 gay/10.5 2"? IN VENTOR. W/ZZ/AM E as? ATTORNEY.

June 15, 11943.. w. P, LEAR AIRCRAFT NAVIGATION INSTRUMENT Filed May 15, 1940 v 7a. w fiU m4 2 Sheets-Sheet 2 INVENTOR. P. 154/? ATTORNEY.

Patented .lnne id 1943 (@l. 25ll-lll) I l'l Claims.

This invention relates to navigational indication systems, and more particularly relates to a novel composite indicator directly solving and simplifying heretofore complex problems in aircrait navigation.

The trend of modern aircraft navigation is towards greater safety and reliability of operations and schedules as Well as towards greater flexibility o1 maneuvering, Efforts have been directed to provide indications to effectively guide the pilot in his navigation despite difidcult terrain or adverse weather conditions such as Wind, rain, fog, and the like. developed complex systemsior these purposes, requiring correlation of a number of separate indications, interpretations, and numerical calculations on the part of the already burdened pilot, as Well as requiring a multitude of special ground radio and associated equipment.

in accordance with the present invention, aircrait navigation is reduced to simple terms, con tinuously adording the pilot automatic pictorial indications of his orientations and maneuvers, reducing even the most advanced problems to simple, readily interpreted indications. The pilot is thus relieved of mental strain and uncer tainty as to position or orientation, and is direct dial heading is readily etlected towards or away irom a radio station, despite cross-Winds or nonvlslbility. The angle of drift of the aircraft due to cross-winds is directly indicated, and automatically corrected for in flight. The composite instrument may be used as a regular 360 automatic radio direction finder and as a directional compass. With the system the pilot is enabled to confidently execute a direct low approach and blind descent onto a runway, regardless of local Weather conditions. For instrument landing, the transmitter is located at the head of the selected runway. 4

The composite navigational indicator comprises a course index held angularly fixed in spaceparallel to the destination of the desired course, and an index giving an accurate bearing on a radio station in the path of the desiredcourse. A further reference index is provided correspondmy to the zero heading or lubber line" of the air- The art, however, has

craft. The desired track index is continuously orientated with a magnetic compass. The radio track index is controlled by a 360 azimuthally compensated automatic radio direction finder system tuned to the charted ground radio station. The composite navigational indicator accordingly performs the functions of a radio direction finder and a directional compass, as Well as the important additional functions referred to above and to be described in detail hereinafter.

The present invention is a continuation-inpart of my copending application entitled "Radio navigation system, Serial Number 313,433, filed January ll, 19%, assigned to the same assignee as the present case. In the copending application, a directional gyroscope is disclosed as v the spatial orienting means for the desired track index. In accordance with the present invention, a magnetic compass is directly incorporated with the composite indicator. otheriorm oi the invention, a master magnetic compass is remotely coupled to the indicator through a telemeterlng arrangement. The desired track index of the composite indicator may be set manually to any desired angular position for spatial orientation and reference. This setting or the desired track index is with respect to the zero degree marl: or the magnetic north inder; of the magnetic compass. The setting oi the desired track is accomplished by shitting a movable scale disk after opening up the indicator instrument. in a modified form of the invention, a novel angular shifting arrangement is incorporated with the telemetering means simplifying the desired track adjustment procedure.

It is accordingly an object of the present inventlon to provide a novel composite navigational indicator system incorporating an automatic radio direction finder and magnetic compass.

Another object oi the present invention is to provide a composite navigational indicator having a novel adjustable course index which is settable through externally accessible means.

ll. further object oi the present invention is to provide a novel desired track index adjusting means for the composite indicator.

These and further objects of the present invention will become more apparent in the following descriptlon of exemplifications thereof illustrated in the drawings, in which:

Fig. l is a diagrammatic arrangement of a preferred embodiment of the navigational sy s tem of the invention.

In an- Fig. 2 is a plan view of the navigational indicator.

Fig. 3 is an elevational view, partly in section,

of one form of the navigational indicator.

Fig. 4 is a perspective illustration of a modified arrangement forthe composite navigational indicator of the invention, incorporating a remote telemetering arrangement and course setting means.

Fig. 5 is a plan view of the composite indicator of Fig. 4.

Fig. 6 is a vertical cross-sectional view through the composite indicator, as taken along the line B5 of Fig. 5.

Fig. '7 is a cross-sectional detail of the'indicator, as taken along the line 'l--'I of Fig. 4.

Fig. 8 is a schematic electrical diagram of the remote telemetering arrangement of the indi cator system corresponding to Fig. 4.

A preferred arrangement which the system of my present invention may assume in practice is diagrammatically illustrated in Fig. 1. The radio direction finder system gives automatic indications over 360 degrees, and may well be the one disclosed in my copending application, Serial No. 286,733, filed July 2'7, 1939, entitled Automatic radio direction indicator, now Patent No. 2,308,521, issued Jan. 19, 1943, and assigned to the same assignee as this case. Equivalent automatic direction finders, capable of operating a bearing indicator over a 360 scale and giving a bearing on a tuned-in radio station, may in stead be used. The illustrated direction finder comprises radio receiver and control circuit unit indicated at Ill, to which is connected non-directional antenna II and rotatable directional or loop antenna I2 through leads I3. A streamline housing about loop antenna I2, indicated in dotted lines at I4, is used to reduce the aerodynamic drag of the loop antenna when mounted exterior of the aircraft. Earphones I5 are connected to direction finder unit III for continuous aural reception, useful for identifying the radio station tuned-in and for obtaining weather reports or landing instructions.

A reversible motor I6 is connected to the control circuit portion of direction finder unit I8 through leads l1, and is energized in accordance with the received radio signals to rotate in either direction in accordance with the sense of the radio signal as determined by the loop antenna I2 when in off-null position with respect to the incoming radio signal waves. The circuits and theory of this operation are described in my Patent No. 2,308,521. 'Motor I5 is coupled to drive loop antenna I2 through electromagnetic clutch I8 electrically connected in parallel with motor I6; reduction gearing I9; worm gearing and quadrantal corrector until 2I interposed between shafts 22 and 22' for loop antenna I2.

Quadrantal corrector unit 2| is used for compensating for non-symmetrical metallic surroundings about the loop antenna, which otherwise would cause false bearing indications. A suitable quadrantal corrector for the unit indicated at 2I is disclosed in my Patent No. 2,296,285, and my copending application Serial No. 344,854 filed July 11, 1940, entitled Quadrantal compensator. An azimuthal or bearing indicator for the direction flnder'is indicated at 25 mechanically coupled to the gear systems I9 to the angular position which loop antenna I2 assumes under the action of motor I6, and as compensated by corrector unit 2 I.

The composite navigational indicator is shown at 30. It is mechanically coupled to loop antenna I2 through flexible mechanical cable 3| directly connected to gearing I9 and indicator 25. The

points out the angular position of the tuned-in radio station. This position directly corresponds indicator 30 is shown in perspective in Fig. 1; in elevation and partly in section, in enlarged Fig. 3; and in plan view, in Fig. 2. Indicator 30 is mounted in the cockpit adjacent the pilot with its scales preferably arranged horizontally. Navigational indicator 30 embodies a magnetic compass arranged to maintain directional scale 32 in predetermined orientations. Directional scale 32 is graduated in 360 degrees, and represents the land reference scale of the composite indicator. The zero index of scale 32 corresponds to the magnetic north index of the magnetic compass.

An enlarged plan view of indicator 30, Fig. 2, shows the preferred arrangement of the respective scales and indices. 'Fig. 3 is an elevational view of the indicator 30 with the cover open, partially broken away to show its details of construction. Directional scale 32 is etched or otherwise inscribed about the top peripheral surface of a turn-table 33 attached to a vertical rod 34 extending from the interior of the magnetic compass mechanism within housing 35 of the unit. The magnetic compass may be of any suitable standard construction, preferably with a slow period of indication and negligible overswing. The zero or magnetic north index N of directional scale 32 corresponds to such indication of the compass with respect to magnetic north. A compensator is preferably included with the magnetic compass as indicated at dotted section 36 thereof, to compensate for local magnetic interference and deviation of the magnetic field. Adjusting screws, indicated at 31, are used for arranging the magnetic compensaton in a well known manner. Lugs 38 project from housing 35 for suitably fastening indicator 3!] in a horizontal position.

The "desired track" index comprises bar 40, preferably of luminous material, inscribed on disk 4|. Disk 4| is adjustably mounted on turntable 33, as with an eyelet 42. Desired track index 40 is set or otherwise manually moved opposite the reading on directional scale 32 corresponding to the angular course it is desired to fly, as will be more fully described hereinafter. The reading of desired track index 40 in Figs. 1 and 2 is 40 (on scale 32) An important feature of the present invention is the correlation of automatic radio directional bearings with desired track indications 40. Towards this end, a radio track index 50, 50' is provided coaxial with the scales and indices of indicator 30. "Radio track index 50, 50' is inscribed on a transparent gear 43, rotatably arranged within lid 44 of the indicator. Transparent gear 43 may be of a plastic material, such as for example the one commercially known as Lucite. Lid 44 is pivoted on hinge 45, and

closes against a rubber gasket 46 on the top pelinden it, it is accordingly oriented by the automatic direction finder system described in connection with Fig. l, to point directly to the radio transmitter tuned to. The bearing accuracy at radio track index 50, 50 is in practice within one degree. There is no directional ambiguity. The angular orientation of radio track index it, til corresponds to the radio hearing indicatlons by needle it of azimuth indicator it. The hearings are ouadrantally compensated through nadrantai compensator ii at the loop antenna.

Head and tail portions t, ha of the radio tracts lnden are preferably of luminous material. Two parallel lines til, or wire or suitable inscrip tion on rear till, connect the radio track index sections til, til. i'ioincident readings of desired track index it and radio track" index it, it are than free of parallax. This is important when the instent is used for accurate straight track navigation.

ii. transparent cover pane or window. is sealed in the top oi" lid dd. Window contains the aircraft zero inden or fined flnhber line relerence linden Reference index: til corresponds to direction of flight oi the aircraft in still ii pictorial representation of an aircraft iii is provided, in alignment reference inden to assist in the pictorial representation and indicator. The arrangement or the scales and as well as the transparent gear :33 supdrive means corresponds to that disclosed in my copendine application, Serial Ilium reierred to alcove, and reierence is hereto for further details of construction.

at opposite fined reference or iuhher line ell calibrated in degrees equally from -er side or zero.

. st a t navigation with the composite indicator composite navigational indicator of the intention automatically and accurately informs pilot loy pictorial indications how host to not" ate the aircrait under all conditions of a. The use of and operation with the composite indicator described herein, incorporatin t" magnetic compass, is equivalent to that de scrihed in my copendinr application, Serial Flum h iililddt, referred to. The substitution or the magnetic compass directly for the arm-compass n, a vacuum drive connection unnecessary. d permits the lid lid to he opened in fliaht for direct manual resetting of desired trac indent Furthermore, resetting or checking of yyro= netic compass always points to magnetic north the reference. The spatial orientation of di-.

sectional scale 32 is corrected for magnetic deviation due to compensator unit til. Zero indeed it of scale points to the magnetic north. The desired trac index it is set opposite thescale readlna on directional scale it to correspond to the desired course to be down, corrected for, macnetic variation of the locality. easterly or wester ly, as will he described hereinafter.

Problems in aircraft navigation are directly resolved with the indicator, relieving the pilot'oi mental strain, calculations and uncertainty. The indications are quickly and easily interpreted, rerinsing the most advanced navigational problems to simple terms. With the system, a pilot can readily fly blind, i. e. by instrument, along any desired radio course, has towards or away from any radio station in any desired radial direction, and traveling a predetermined straight track over the ground regardless of wind force invention serves as the usual directional magnetic compass in the aircraft, thus eliminating the installation of a separate one. The automatic uni-directional 360 radio course indicator incorporated in the system may be used independently as such for homing, and radio directional flight in general. ii distinct indication is obtained when the aircraft passes over the radio station, by a 180 reversal of the radio track linden (til, hit). The system is also most advantageously used for edecting a low approach and instrument landing on a selected runway.

Only a single ground radio transmitwr station is necessary for navigation with the instrument oi the invention. The largest airliner, loomher or clipper may he navigated on a straight-trach to any out-of-the-way airport having a simple radio transmitter and safelyblind-landed on the local airport or seaport. The pilot simply tunes-in the radio station, ascertains the selected course or runway in degrees, sets his desired tracir index iii accordingly, and is then prepared to effect a direct instrument approach and tie-- scent to the runway. The navigation and landing maneuvers are rendered foolproof and safe regardless of wind velocity or other weather conditions. Reference is made to figs. ii to l? and the attendant description in my copending application, Serial Numher 313,433, for an exposition of the uses and advantages oi the composite indicator corresponding to the present invention.

The hasic principle oi the indications or the system or the invention is readily comprehended by the pilot. it consists in correlating:

(ii A desired track index; continuously held singularly lined in space parallel with the course desired (although movable with respect to the aircraft) l (2) A continuous radio hearing on a transmitter on the desired course;

(3) A luioloer line iii], the stationary reference index of the aircraft itself. 1

Each indication may he used independently of the other. However, when correlated, they directly and automatically resolve even the most complex navigational problems for the pilot. Pilot training time is irept at the minimum, and maneuvering emciency is increased to a manimnm.

Straight tracir. navigation towards a radio station is efiiected, automatically compensated for drift due to cross-winds, by maintaining radio tracts index it coincident with desired traclr index iii. The ancle which coincident indices it and hit makes with "luloloer line" is the drift angle at the aircraft, indicating the attitude of the aircraft with respect to the course of flight. The pilot, in a car manner, can any a predetermined straight track in any radial direction away from a radio station by heeping tail iii of necessary to complete the whole system, which station may be a commercial broadcast station, simple voice transmitter, Coast Guard station, radio range, etc.

The setting in degrees of desired track" index 40 with respect to directional scale 32 depends on several navigational factors. The desired track is identical in degrees with the "magnetic compass course" for the destination, in degrees. The primary factor entering into the determination of the magnetic compass course" and the desired track" is the geometric bearing in degrees of the course or destination of flight with respect to true north. Such true bearing is generally termed the true course." The easterly or westerly magnetic variation, in degrees, for

the vicinity, is respectively subtracted from or added to the true course, to derive the magnetic course." Where a magnetic compensator 36 is not used, deviation in degrees of the.actual magnetic compass readings from true magnetic readings is used to correct the magnetic course" to derive the desired magnetic compass course or generally termed "compass course. With the compensator the magnetic deviations are automatically accounted for.

The compass course" is the degrees as read on a magnetic compass for straight alignment to a destination from a given position. The significance and mode of determination of the compass course in degrees is well known to those versed in the art of navigation, and is clearly explained in Chapter III of the publication Practical Air Navigation by Thorburn C. Lyon of the U. S, Department of Commerce,

published in 1929 by the U. S. Government Print ing Office, Washington, D. C. The desired track index 40 is adjusted to read the compass course" for the destination, in degrees, on directional scale 32. This is performed by opening up lid l4, and manually rotating disc ll until index 40 reads properly on scale 32. An arrangement for adjusting index 40 without opening up lid Al is disclosed hereinafter in connection with the modified form of the invention, shown in Figs. 4 to 8.

Modified composite indicator arrangement A modified arrangement for the composite indicator is shown in perspective at 19 in Fig. 4. In indicator 10 the adjustment of desired track" index 40, in accordance with the course to be navigated, is performed without opening up the instrument. The adjustment is performed through movable scale ll, visible behnd slotted opening 12 in lower casing section 13. "Desired track index 40 is adjusted by simply turning scale 19 with respect to index mark 14 on casing 13, as will be presently described. Composite indicator"!!! contains a radio track index 50, 59, geared through flexible cable 3| to an automatic direction finder unit such as described in connection with Fig. l. affording continuous azimuthal radio bearings with respect to the radio station tuned-in, and readon outer concentric scale I5. Fig. 5 shows the composite scales of indicator 10 in enlarged plan view.

The composite indicator unit 10 does not contain a directional compass, corresponding to the magnetic compass of the unit 30 previously de scribed, or corresponding to the directional gyro disclosed in my copending application, Serial Number 313,433. In accordance with the modified form of the invention, the master directional compass unit of the vehicle isused, which may be remote from the composite indicator 10. In. Fig. 4, a master magnetic compass I6 is shown, which may be of any standard type. Magnetic compass 16 contains the usual pointer 11. A compensator unit schematically indicated at 18 is preferably incorporated with the magnetic compass. The rotatable portion of the magnetic compass 16, connected to pointer TI, is coupled with the composite indicator l0 through a telemetering system. An electrical telemetering arrangement is shown, specifically a direct current telemetering system of the Selsyn type.

The telemetering transmitter is shown at 80, coupled to the movable pointer mechanism of the compass by shaft 8|, as schematically indicated in dotted lines. The transmitter Bil is connected by electrical cable 82 to a translator or repeater unit incorporated within indicator 10. VA direct current source a: is in circuit with transmitter,

. is in the latter case coupled to the directional gyro, for example in a manner such as illustrated in Fig. 8 of my copending application Serial No. 313,433 referred to.

Cross-sectional Fig. 6 through indicator III shows the arrangement thereof for telemetering the directional compass bearings to the indicator, and the novel means for adjusting the "desired track index 00. Transparent radio bearing gear 43 is rotatably mounted'in the upper casing section 84 of instrument II; and contains "radio track" index 50, 50'. Cover pane or a window 55' at the top of casing section I4, contains reference or lubber line" index 6|, aircraft representation GI and fixed 360 azimuthal scale I5.

A tum-table 85 is rotatably supported within instrumentlll and is coupled to the rotor 85 of the telemetering repeater unit by shaft 81. The lower extending portion 81' of the rotor shaft 81 is supported in central bearing element 88 secured to the base 90 of instrument 10. A supporting spider 9| contains central bearing element 92 for supporting rotor shaft 81. Tum-table 85 has the desired track index 49 inscribed on its exposed upper surface. A reference scale 95 is marked in degrees on either side of index 40. The drift or crab angle of the aircraft in flight is derived directly from reference scale 95 when read with respect to "lubber line" 60. Such reading is taken when "desired track" index 40 is coincident with radio track" index 50, signlfying straight track navigation with instrument 10.

A tubular member 93 is rotatably supported within composite indicator 10. Member 93 is preterably of insulation material, such as Bakelite or other suitable composition. The toroidal stator winding 98 of the repeater unit is encased ported in an insulation block 99 mounted in casing section 94. Brushes individually coact with slip rings I00 mounted about tubular member 93. Slip rings. I90 are connected to stator coil 95 through wires llli.

Tubular member 93 contains an annular extension I92 slidably arranged between central casing section 94 and base 90 of instrument I0. A concentric. groove I03 is cut in member 83 to reduce its frictional drag on the inner surface of base 90, and forming two spaced concentric annular leg portions I04, I05 for sliding thereon. The outer ends of spider 9| are supported on member 93 to in turn hold turn-table B5 and rotor 06 in rotatable alignment centrally of instrument 110. The casing of instrument l comprises upper section 84, central section 94 and bottom section l3 containing base 90. Upper and lower sections 84 and i3 overlap central section 94, being joined thereto by screws I05. Rotatable member 93 is thus stably supported within the housing of instrument I0, and carries stator coil 96 of the repeater unit in continuous electrical relation with brushes 96 connected to cable 82 of the telemetering system. Partial sectional view Fig. '7 shows movable scale It projecting through slotted opening 12 in lower casing section it. The setting of tubular member 93, and associated stator winding 95, is accomplished by manual operation of projecting scale M.

Fig. 8 is a schematic electrical diagram of the telemetering arrangement between the rotatable section ti of master compass it, and turn-table at of the composite indicator. The rotatable compass element. schematically represented in Fig. 8 by shaft 3i coupled to compass pointer ll, is .connected to brush carrier Hit of transmitter 80 through spider ill. Brushes H2, H2 coact with toroidal stator winding tilt of transmitter 30. Battery 83 is connected between brushes Ht, lit. Equi-distant taps Hilton winding M properly'connect winding M5 to threewire cable 82. Stator winding i it of transmitter 80 and stator winding tit of the repeater unit within instrument it are thus in continuous connection through three-wire cable 82.

In accordance with the modified form of the invention, stator winding 9% of the repeater unit is displaceable in space phase with respect to fixed stator winding N5 of transmitter $0. The space phase displacement is accomplished by turning member at within indicator unit it through exposed scale it. The amount of the space phase displacement corresponds to the rotation of scale it, indicated by index it on the indicator casing as shown in Fig. 4. Scale ll is graduated in 360. Its 0 position on index it corresponds to a zero or no space phase displacement between the position of rotor tt of the repeater unit, and the rotor of transmitter 80 coupled to compass needle ll.

The displacement of scale it in Figs. 4 and 5 is 40 counterclockwise. Rotor 86, carrying turntable at, is accordingly displaced 40 counterclockwise, representing a space phase displacement with respect to the readings of the master compass it. A 360 compass scale H25 is inscribed on the upper peripheral surface of tubular member 93. Scale W5 is concentric between outer 360 azimuthal scale 15, and inner reference scale 95, on turn-table 85. The reading of scale "it opposite the zero reference index I20 of fixed scale l5, represents the actual angular displacement of member 93 from its zero position. This reading of scale H25 in Figs. 4 and 5 is 40, which is the same as the reading of scale H opposite index I4. Since repeater stator winding 95 is fixed in and carried by member 93, its space phase displacement with respect to its zero position is identical with that of member 93.

The positions of repeater rotor 86, and therefore tum-table 85, is accordingly altered by an amount equal to the space phase displacement in its transmission of the readings of the master compass 16. In the illustrated case, desired track index 40 is oriented 40 less than the readings on the master compass due to the 40 counterclockwise rotation of scale II. It is to be understood that for any different setting of scale I I, "desired track index 40 will be altered by a corresponding amount with respect to the readings of the master compass. The 30 reading of needle ll of magnetic compass 16 shown, is accordingly translated as a 350 indication of desired track index 40 with respect to the fixed azimuthal scale 15 of the composite indicator [0. The actual reading of the remote compass I6 may be directly ascertained on composite indicator 10 by noting the indication of desired track" index 40 on the central 360 directional scale I25. a

The composite indicator 10 may be used for the various navigational maneuvers described hereinabove in connection with indicator 30; and also those described in my copending application, Serial Number 313,433. The adjustment of desired track index 40 is accomplished on indicator ill by simply moving scale it with respect to index it to impart the proper orientation thereof in accordance with the principles of operation of the system previously described. By coupling a plurality of composite indicators of the type to a master automatic direction finder system (through appropriate flexible cables corresponding to M), and to a master compass or directional gyroscope (through suitable telemetering arrangements), a pilot, co-pilot, navigator as well as other persons aboard a large airship, may have individual indicators. Such plural indicator system is economical of master directional equipment and insures uniform indications throughout.

Although I have described preierred embodiments for carrying out the principles of my present invention, it is to be understood that modifications thereof, both as to construction and operation, may be practiced without departing from the broader principles and scope of the invention, as expressed in the following claims.

.What I claim is:

1. In a navigational system having an automatic radio direction finder and a directional compass: a composite indicator oi the character described comprising a radio track index for coupling with the automatic radio direction finder to indicate the bearing to a radio transmitter, a desired track index coaxially arranged with said radio track index, a telemetering arrangement including a repeater unit connected to said desired track index and responsive to a transmitter unit coupled to the compass to spatially orient the desired track index in correspondence with indications of the compass, said telemetering arrangement having mean: for effecting a preferred spacephase displacement between said units for correspondingly altering indications of said desired track index with respect to indications of said radio track index.

2. In a navigational system of the character described, the combination of automatic radio direction finding means responsive to signals re- .ceived from a radio transmitter, a directional compass, a composite indicator comprising a radio track index and a desired track index coaxially arranged, mechanism coupling said radio track index with said direction finding meansifor continuously indicating the bearing to e radio transmitter an electrical telemetering device remotely coupling said desired track index with said compass for spatially orienting said desired track index in accordance with indications of said compass, said telemetering device having means for electrically adjusting the space phase therein for correspondingly altering the indications of said desired track index with respect to indications of said compass.

. 3; In a navigational system of the character described, the combination of uni-directional automatic radio direction finding means responsive to signals received from a radio transmitter including motor means operable in accordance with the bearing direction of the signals, a directional compass, a composite indicator comprising a radio ,track index and a desired track' index coaxially arranged, mechanism coupling said radio track index with said motor means for continuously indicating the bearing to the radio transmitter over 360 of arc, an electrical telemetering device remotely coupling said desired track index with said compass for spatially orient ing said desired track index in accordance with indications of said campass, said telemetering device having means for adiusting the space phase between the indications of said desired track index with respect to indications ofsaid compass.

4. In a navigational system having a unidirectional automatic radio direction finder including motor means operable in accordance with the bearing direction of received radio signals,

and a directional compass: a composite indicator of the character described comprising a radio track index for coupling with said motor means to indicate the bearing to a radio transmitter over 360 of are, a desired track index 00- axially arranged with said radio track index on vi the indicator, a telemetering repeater unit mounted in the indicator and directly coupled to said desired track index, said repeater unit being connectable to a telemetering transmitter at the compass to spatially orient the desired track inthat in correspondence with indications of the compass, said telemetering repeater unit containing means for eifecting a preferred space phase displacement between indications of said desired track index with respect to indications of said over 360 of arc, a desired track index coaxially ;.arranged with said radio track index, a telemetering arrangement including a repeater unit rigidly connected to said desired track index and responsive to a transmitter unit coupled to the compass to spatially orient the desired track index in correspondence,with'indications of the compass, said telemetering arrangement having means for effecting a preferred space phase displacement between said units for correspondingly altering indications of said desired track index with respect to indications of said radio trackindex.

6. In a navigational system of the character described, the combination of uni-directional automatic radio direction finding means responsive to signals received from a radio transmitter including motor means operable in accordance netic compass, a composite indicator comprising a radio track index and a desired track index coaxially arranged, mechanism coupling said radio track index with said motor means for continuously indicating the bearing to the radio transmitter over 360 of are, an electrical telemetering device including a transmitter coupled to said compass and a repeater coupled to said desired track index for spatially orienting said desired track index in accordance with indications of said compass, said telemetering device having means for adjusting the space phase between said transmitter and said repeater for correspondingly altering the indications of said desired track index with respect to indications of said compass.

7. In a navigational system having a uni-directional automatic radio direction finder including motor means operable in accordance with the bearing direction of received radio signals, and a directional compass: a composite indicator of the character described comprising a radio track index for coupling with said motor means to indicate the bearing to a radio transmitter over 360 of arc, a scale concentric with said radio track index, a desired track index rotatably arranged coaxially with respect to said scale, a telemetering arrangement including a repeater unit rigidly connected to said desired track index and responsive to a transmitter unit coupled to the compass to spatially orient the desired track index in correspondence with indications of the compass; said the bearing direction of received radio signals;

and a directional compass: a composite indicator of the character described comprising a radiov track index for coupling with said motor means to indicate the bearing to a radio transmitter over 360 of arc, a 360 scale concentric with said radio track index, a desired track index rotatably arranged coaxially with respect to said scale, a telemetering arrangement including a repeater unit connected to said desired track index and responsive to a transmitter unit coupled to the compass to spatially orient the desired track index in correspondence with indications of the compass; said telemetering arrangement having means for effecting a preferred angular displacement of indications of said desired track index with respect to said scale, and a second'360 scale attached to said means for angular displacement thereby in accordance with that effected between said um'ts, said second scale being arranged to be visible with and concentric with said'indices and positioned between said first mentioned 360 scale and said desired track index to constitute a compass bearing reference therefor.

9. In a navigational system having an automatic radio direction finder and a directional compass: a composite indicator of the character described comprising a radio track index coupled to the automatic radio direction i inder for indicating the bearing to a radio transmitter, a desired track index coaxially arranged with said radio track index, a casing for said indicator, an electrical telemetering repeater unit rotatably mounted in said casing and coupled with said desired track index, said repeater being electrically with the bearing direction of the signals, a magresponsive to a telemetering transmitter at the directional automatic radio direction finder in cluding motor means operable in accordance with the bearing direction of received radio signals, and a directional compass: a composite indicator of the character described comprising a radio track index for coupling to said motor means to indicate the bearing to a radio transmitter over 360 of arc, a casing for said indicator, 9. scale for said radio track index attached to said casing, a desired track index coaxially arranged with said radio track index and said scale, a telemeterin repeater unit mounted in the indicator and coupled to said desired track index, said repeater unit being connectable to a telemetering transmitter at the compass to spatially orient the desired track index in correspondence with indications or the compass; said telemetering repeater unit containing means for effecting a preferred space phase displacement of indications by said desired track index with respect tosaid scale.

ll. In a navigational system having a unidirectional automatic radio direction finder and a directional compass: a composite indicator of the character described comprising a radio track index for coupling to said automatic radio direction finder to indicate the bearing to a radio transmitter over 360 of arc, a casing for saidindicator', a scale for said radio track index attached to said casing, a desired track index coaxially arranged with said radio track index and said scale, an electrical telemetering repeater unit having its stator rotatably mounted in said casing and its rotor coupled with said desired track index, said repeater being electrically responsive to a telemetering transmitter at the compass to spatially orient the desired track index in correspondence with indications of the compass, and means for angularly displacing said stator with respect to said casing to correspondingly effect a 7 space phase displacement of indications by the desired track index with respect to said scale.

12. In a navigational system having an automatic radio direction finder and a directional compass: a composite indicator of the character described comprising a radio track index for coupling with the automatic radio direction finder to indicate the bearing to a radio transmitter, a desired track index coaxially arranged with'sa d radio track index. an electrical telemetering repeater coupled with said desired track index, said repeater being connectable with a transmitter at thecompass for spatially orienting the desired track index in correspondence with indications of the compass. said repeater comprising a rotatably mounted element, a winding mounted on said element, and a rotor cooperative with said winding and fixedly coupled with said desired track index, means for effecting a displacement between indications of said desired track index and indications of said radio track index, said means embodying an instrumentality on said element in electrical connection with said winding, and members mounted on said indicator in continuous electrical contacting relation with said instrumentality and winding.

13. In a navigational system having an automatic radio direction finder anda directional compass: a composite, indicator of the character describedcomprising a radio track index coupled .to the automatic radio direction finder for indicating the bearing to a radio transmitter, a desired track index coaxially. arranged with said radio track index, a casing for said indicator, an electrical telemetering arrangement coupling said desired track index with the compass for spatially orienting the desired track index in correspondence with indications of the compass: said telemetering arrangement comprising an element rotatably supported in said casing, a winding secured to said element, and a rotor cooperative with said winding and secured with said desired track index, and means for effecting a preferred space phase displacement of indications of said desired track indexand indications of said compass, said means embodying slip rings on said element in electrical connection with said winding and brushes insulatingly mounted on said casing and in continuous electrical contact with said slip rings and winding.

14. In a navigational system having an automatic radio direction finder and a directional compass: a composite indicator of the character described comprising a radio track index coupled to the automatic radio direction finder for indicating the bearing to a radio transmitter, a desired track index coaxially arranged with said radio track index, a casing for said indicator, an electrical telemetering arrangement for coupling said desired track index with the compass for spatially orienting the desired track index in correspondence with indications of the compass; said telemetering arrangement comprising an element rotatably supported in said casing, a winding secured to said element, and a rotor cooperative with said winding and secured with said desired traclr index; and means for eflecting a preferred space phase displacement of indications of said desired track index and indications oi said compass, said means embodying slip s on said element in electrical connection with said windingand brushes insulatingly mounted on-said casing and in continuous electrical contact with said slip rings and winding, and with a telemetering transmitter attached to a movable index oil said compass, a portion of said element extending to the exterior of said indicator for manual rotatable adjustment thereof to effect the space phase displacement.

15. In a navigational system having a uni- I dex with the compass for spatially orienting the desired track index in correspondence with indications of the compass, said telemetering arrangement comprising an element rotatably supported in said casing, a' winding mounted on said element; and a rotor cooperative with said windin and fixedly coupled to said desired track index; and means for eflecting an angular displacement of indications of said desired track index with respect to indications of said compass, said means embodying apparatus on said element in elec-' trical connection with said winding and contact members insulatingly mounted on said casing in continuous electrical contact with said apparatus and winding; an annular portion of said element extending to a slot in said casing for manual rotatable-displacement thereof; and a scale on the extending element portion for indicating the angular displacement of said element with respect to a zero index on said casing,

16. In a navigational system having a unidirectional automatic radio direction finder and a directional compass: a composite indicator of the character described comprising a radio track index for coupling to the automatic radio direction finder to indicate the bearing to a radio transmitter over 360 of arc, a casing for said indicator, a scale for said radio track index attached to said casing, a desired track index coaxially arranged with said radio track index and said scale; an electrical telemetering arrangement for coupling said desired trac index with the compass for spatially orientin the desired track index in correspondence with indications of the compass, said telemeterlng arrangement comprising an element rotatably supported in said casing, a winding mounted on element, and a rotor cooperative with said winding and positively coupled to said desired track index; and means associated with said telemetering arrangement for efl'ecting a preferred space phase displacement of indications of said desired track index with respect to indications of said compass; said means containing an instrumentality on said element in electrical connection with said winding, members insulatingly mounted on said casing in continuous electrical contact with said instrumentality and winding, said members being connectable with a telemetering transmitter unit attached to amovable index of the compass; a portion of said element extending to a slot in said casing for rotatable adjustment. thereof and a 360 scale on said element concentric with the indices, and constituting a compass bearing reference for said desired track index.

17. In a navigational system having a unidirectional automatic radio direction finder and a directional compass: a composite indicator of the character described comprising a radio track index for coupling to the automatic radio direction finder to indicate the bearing to a radio transmitter over 360 of arc, a casing for said indicator, a scale for said radio track index attached to said casing, a disc containing a desired track index coaxially arranged with said radio track index and said scale; an electrical telemetering arrangement coupling said disc with the compass for spatially orienting the desired track index in correspondence with indications of the compass, said telemetering arrangement comprising an element rotatably supported in said casing, a winding mounted on said element, and a rotor cooperative with said winding and coupled to said disc; and means for efiecting an angular displacement between indications of said desired track index and indications of said compass, said means embodying slip rings on said element in electrical connection with said winding, and brushes insulatingly mounted on said ceasing in continuous electrical contact with said slip rings and winding, said brushes being connectable with a telemetering transmitter unit attached to a movable index of the compass; an annular portion of said element extending to a slot in said casing for manual rotatable displacement thereof, a 360 scale on the extending element portion for indicating the angular displacement of said element with respect to a zero index on said casing; and a compass rose on said element arranged concentric with said indices and positioned between said first mentioned scale and said disc, constituting a compass bearing reference for said desired track index.

-- I WILLIAM P. LEAR. 

